1. Field of the Invention
This invention relates to photographic cameras of the collapsible type.
More particularly, the invention relates to a collapsible camera wherein a film transporting mechanism is operated in response to relative movement of the camera body and a lens mount which is connected to the same.
2. The Prior Art
Various proposals have been made for transporting film in still cameras, particularly in the types of cameras which are generically known as instant-picture cameras. It has been suggested to use an electrically operated transporting mechanism, or to utilize a crank which is turned by hand when film is to be transported. Slidable elements have been proposed in lieu of the crank.
In one camera which is collapsible, i.e., where a lens mount is movable relative to the camera body between a collapsed (shut) and an extended (open) position, the proposal has been made to effect film transportation as a function of the movement of the lens mount relative to the camera body. This can be done by e.g., providing an arcuate gear segment which pivots with the lens mount about a pivot axis thereof and which drives a step-up gearing that in turn rotates a set of film transporting rollers.
This is basically a rather satisfactory proposal. It does, however, have some disadvantages which require correction. The recent public demand is for smaller and more compact cameras. The size limitations which are imposed on camera housings by this requirement make it impossible to use a relatively large arcuate gear segment. On the other hand, the relatively small gear segments which can be accommodated in these scaled-down housings have two problems: the length of their serrated arcuate periphery (from which motion is transmitted to the film transporting mechanism) is generally insufficient to effect film advancement over the requisite distance during a single movement of the lens mount relative to the body -- and the forces acting on these short-radius segments are so high that it is impracticable to make the segments of inexpensive (but relatively low-strength) materials, such as synthetic plastics. This latter factor is especially important in instant-picture cameras where the film transporting mechanism includes a pair of nip rollers which not only advance each film but squeeze developer fluid out of a pouch at one end of the film to spread it (during film transport) over the film area to be developed; this requires substantial force which must be transmitted to the mechanism via the gear segment.